ADSM-L

Re: Calculate size of uncompressed Files

2000-01-17 12:16:37
Subject: Re: Calculate size of uncompressed Files
From: Andrew Taylor <AndrewTaylor2 AT HALIFAX.CO DOT UK>
Date: Mon, 17 Jan 2000 17:16:37 -0000
Thomas,

I can see nothing in any tablespace columns that would achieve this result,
it looks like the compression ratio is recorded to the activity log and
schedule log at backup time and that is that, log retention times pass and
pffft, gone.

I'd love to be proved wrong, as the way I did it when asked for an
uncompressed total was to estimate using the current backup compression
ratios and occupancy details for each server type - not perfect, as files
that change regularly will not necessarily give the same compression ratios
to those that backed up on day 1 and have changed rarely since. Also, if
you're looking for an overall total, the ratio may be heavily biased by the
compression on just a few clients, for instance the full backups of Oracle
databases. These ratios in turn are highly dependent on how much data is in
the database - typically a full backup on a new Oracle server may compress
as high as 99% on day 1, but this then drifts downwards with time. If you
are retaining just one or two recent full backup copies, the current
compression achieved on each server should be a pretty good measure of what
is currently sitting on tape.

I'm no statistician and the comments are very much based on 'back of an
envelope' calculations, I'd be interested if there is any best practice
regarding such estimates - perhaps as a by-product of using client
compression many of us are under reporting the scale of what we backup and
what we store.


Andrew Taylor,
Halifax plc,
Yorkshire,
UK

andrewtaylor2 AT halifax.co DOT uk

This message is attributable to the sender and does not necessarily reflect
the view of Halifax Group plc or its subsidiaries






> ----------
> From:         Rupp Thomas (Illwerke)[SMTP:thomas.rupp AT ILLWERKE DOT AT]
> Reply To:     ADSM: Dist Stor Manager
> Sent:         14 January 2000 19:48
> To:   ADSM-L AT VM.MARIST DOT EDU
> Subject:      Calculate size of uncompressed Files
>
> Hi *SM-ers,
>
> we compress files before sending them to the *SM server.
> When I do a SELECT SUM(PHYSICAL_MB) FROM OCCUPANCY
> I get the sum of the compressed sizes of the saved files.
> Is there a way to get the uncompressed sizes?
>
> I would like to create a statistic like
>
> Total Storage Used Storagepool TAPE (compressed):     224.893,78 MB
> Total Storage Used Storagepool TAPE (uncompressed): 449.787,56 MB
>
> Is this possible?
>
> Kind regards
> Thomas Rupp
> UIS- Informatik Services
> Vorarlberger Illwerke AG
> MAIL:   thomas.rupp AT illwerke DOT at
> TEL:    ++43/5574/4991-251
> FAX:    ++43/5574/4991-820-8251
>

 01/17/00 17:16:54
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Part of the Halifax Group, Halifax Group plc, Registered in England No. 
2367076.  Registered Office: Trinity Road, Halifax, West Yorkshire HX1 2RG. 
Represents only the Halifax Financial Services Marketing Group for the purposes 
of advising on and selling life assurance, pensions and unit trust business.  
The Marketing Group is regulated by the Personal Investment Authority.  
Switchboard 01422 333333.


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